Coupling quantum emitters in WSe2 monolayers to a metal-insulator-metal waveguide

Abstract

Coupling single photon emitters to surface plasmons provides a versatile ground for on chip quantum photonics. However, achieving good coupling efficiency requires precise alignment of both the position and dipole orientation of the emitter relative to the plasmonic mode. We demonstrate coupling of single emitters in the 2-D semiconductor, WSe2 self-aligned with propagating surface plasmon polaritons in silver-air-silver, metal-insulator-metal waveguides. The waveguide produces strain induced defects in the monolayer which are close to the surface plasmon mode with favorable dipole orientations for optimal coupling. We measure an average enhancement in the rate of spontaneous emission by a factor of 1.89 for coupling the single defects to the plasmonic waveguide. This architecture provides an efficient way of coupling single photon emitters to propagating plasmons which is an important step towards realizing active plasmonic circuits on chip.In recent years, defects bound excitons in two dimensional semiconductors have emerged as a new class of single photon emitters with ultra-narrow linewidths of 100 µeVs, as well as high single photon purity. [1][2][3][4] These emitters are located at the surface of an atomically thin monolayer which allows them to come in close proximity to photonic nanostructures. Another characteristic feature is that they can be deterministically induced by strain engineering allowing for site specific positioning. 5-7 Thus, with the ability to position these atomically thin quantum emitters, one can efficiently couple to the confined mode of optical nanostructures providing a platform for coherent light-matter interactions. Such a platform is critical for applications such as quantum communication and quantum information processing 8,9 . 2D materials with their narrow linewidths and flexibility in terms of positioning, offer a promising path to tailoring strong light matter interactions. However, apart from nanoscale positioning of emitters, the nanostructure must also exhibit a high optical density of states. A strong contender for the photonic nanostructures are surface plasmon polaritons generated at a metaldielectric interface. Surface plasmons exhibit extreme subwavelength confinement of light 10,11 and an atom-like dipole emitter placed near the metal-dielectric interface, preferentially emits into the surface plasmon mode due to its high optical density of states. 12 The strong optical decay of emitters into the surface plasmon results in efficient coupling of emitters to a common plasmonic mode that can lead to strong photon-photon interactions. 13 Coupling also produces a significant enhancement in the rate of spontaneous emission of the emitters 12,14,15 which can help realize a fast single photon source on-chip. Thus, single photon emitters in 2D materials, coupled to surface plasmon polaritons establishes a platform for compact active photonic circuits essential for quantum information processing [16][17][18] .Several previous works reported deterministic coupling of quantu...

Enabling remote quantum emission in 2D semiconductors via porous metallic networks

“…14 This opens opportunities for coupling and/or energy routing between SPE sites in 2D semiconductors for potential applications such as on-chip quantum light sources. [15][16][17] In addition, metal nanostructures can lead to enhanced Purcell factors resulting in increased single-photon emission rates. 9,18 As such, it is natural to imagine interfacing 2D semiconductor SPEs with metals to advance quantum and optical processing technology.…”

Single photon sources from two dimensional materials and their interfacing with plasmonic waveguides

“…Due to these in-plane com-ponents, coupling efficiency is increased effectively. As realized by Subhojit Dutta et al [40] a coupled system of propagating surface plasmons in metal insulator metal waveguide (silver-air-silver) to single photon emitters in W Se 2 (Fig. 8(c)).…”

Two‐Dimensional Materials for Integrated Photonics: Recent Advances and Future Challenges

“…[316] On-chip quantum emitters based on WSe 2 integrated with the metal waveguide were also demonstrated. [317,318] However, the majority of quantum emitters based on TMDCs are only working at cryogenic temperatures. Recent studies indicated that h-BN was an alternative material for room-temperature quantum emitters.…”